Patent GB-1027441-A (GB)
Title: Pulse senders
IPC: H04Q3/00
Filed: 1963-01-10
Abstract: 1,027,441. Automatic exchange systems. WESTERN ELECTRIC CO. Ltd. Jan. 10, 1963 [Jan. 15, 1962], No. 1108/63. Heading H4K. In a pulse sender arrangement in which digital information is sent alternately from digit registering means to two portions of a scanning circuit which are scanned alternately, one portion being scanned for transmission, whilst connections are being made to the other portion preparatory to sending the next digit, provision is made to maintain this alternating sequence despite the deletion of some digits or the insertion of others. The transmission takes place using six pulse positions per digit, frequency shift of a V.F. signal occurring in two of these positions determined by the value of the digit. When a marker takes the sender into use it feeds thereto all the digits in question (received on groups of relays A0 . . . A7, BO. . . . B7, . . .) the number of these digits to be deleted (these digits always being the earliest in the sequence) and any additional digits to be inserted (received on groups of relays AR0 . . . AR7, BRO . . . BR7, CR0 . . . CR7). The number of digits to be deleted isindicated to a series of relays DL1 . . . DL6 (not shown) and a relay DAR, DBR, DCR (not shown) is operated for each additional digit to be inserted. Under control of these relays a relay AEV is operated if an even number (including 0) of digits is to be inserted and a relay DLOD is operated if an odd number of digits is to be deleted. The digital information on AR0 . . . AR7, . . . A0 . . . A7, . . . is fed to the upper and lower groups of wires by digit steering relays ARS . . . CRS, AS . . . LS which are operated in succession by a steering circuit, Fig. 6 (not shown), which brings up such relays as are required in succession under control of DL1 . . . DL6 and DAR . . . DCR, each relay coming up in one scanning period and remaining up in the succeeding one during which the digit in question is transmitted. Each transmission commences with a start signal provided by relay KP to the left-hand portion of the scanning circuit 25 and this scanning cause the transmission by the pulse sender of a 5-out-of-6 V.F. start signal. Assuming no insertions or deletions are to take place (so that DLOD is down and AEV is up) steering relay AS during this period connects up the A digit information to the lower circuit whence it passes via make contacts of AEV to the upper circuit to the right-hand portion of the scanning circuit. Next, BS operates to connect the B digit information to the upper circuit and thence via make contacts of AEV to the left-hand portion and so on the digits passing alternately to the right and left-hand portions of the scanning circuit. Finally, when all digits have been sent, STS connects up a characteristic code to permit a 2-out-of-6 V.F. signal indicating end of sending. Clearly if an odd number of digits is to be inserted, then the digital information has to be sent to the opposite sides of the scanning circuit as compared with the previous case and this is effected by the non-operation of AEV. Likewise, if an odd number of digits is to be deleted a similar reversal must take place and this is effected by the operation of DLOD.